The Scientific Core (Core B), will coordinate the use of mAbs and Ig fusion proteins for studying the expression and function of TIM proteins in T cell activation and tolerance. These reagents will be an easily accessible means of addressing the functions of these important immunoregulatory pathways. The major goals of the Scientific Core are to generate novel reagents that facilitate the analysis of the expression and function of TIM family members and to serve as a repository for and provide existing reagents for the PPG Projects. The availability of large quantities of mAbs and Ig fusion proteins Is critical to the success of Projects 1-4. MAbs will be used to visualize the expression of TIM family members and as pathway agonists and antagonists. Ig fusion proteins will be used for expression, function, and signaling studies. In addition, Ig fusion proteins may serve as a means to specifically block receptor/ligand interactions. To accomplish these goals, the Scientific Core has two aims: Specific Aim 1: To generate novel monoclonal antibodies and Ig fusion proteins to study the function and expression of TIM family members. Specific Aim 2: To serve as a repository and maintain and produce existing and newly generated TIM mAbs and Ig fusion proteins for PPG investigators. The production of these critical reagents by a core not only will be time and cost efficient, but also provide standardized reagents that will facilitate comparison of data by Investigators in this PPG.